In recent years, as an illumination device that replaces incandescent lamps, an illumination device (for example, a light-emitting diode (hereinafter also referred to as “LED”) bulb) using a LED as a light source has been developed in view of energy saving, environmental conservation and the like. However, in comparison with light emitted from incandescent lamp, light emitted from an LED has high rectilinearity. Therefore, to use an LED bulb in the same manner as incandescent lamps, it is important to distribute the light emitted from the LED to the forward direction, the lateral direction and the rearward direction with a good balance.
As such an illumination device, an illumination device is known which has a plurality of LED modules, and a lens for controlling the light distribution of the light emitted from the LED modules (see, for example, PTL 1), for example. FIG. 1 is a perspective view of LED module 10 and lens 20 disclosed in PTL 1. The illumination device disclosed in PTL 1 includes a substrate not illustrated, seven LED modules 10 disposed on the substrate, and annular lens 20 disposed on the upper side of seven LED modules 10. One of LED modules 10 is disposed on the central axis of lens 20, and the remaining six LED modules 10 are disposed in an annular form around the LED module 10 disposed on the central axis of lens 20. Lens 20 includes incidence surface 21 on which light emitted from LED module 10 is incident, and emission surface 22 configured to emit the incident light. Incidence surface 21 is disposed to face LED module 10 in annular lens 20. Emission surface 22 is disposed on the outer side in annular lens 20. Lens 20 allows incidence of a part of light emitted from LED module 10 on incidence surface 21, and emits the light from emission surface 22 in the forward direction, the lateral direction and the rearward direction. In addition, annular lens 20 allows another part of the light emitted from LED module 10 to pass therethrough via a hollow part in the forward direction. As described, the illumination device disclosed in PTL 1 can distribute the light emitted from LED module 10 in the forward direction, the lateral direction and the rearward direction.